Previously I wrote an article discussing the importance of mobility and stability functionally. To quickly recap, the joint-by-joint approach discusses where in the body we need stability and where we need mobility. In the cases where we don’t have appropriate stability or mobility, the joints on either side will try and pick up the slack so we can still achieve our projected outcome. It only seems fitting that the low back be discussed first as it is a huge disabling feature in our society.
Without even concerning the muscles and other soft tissue structures that surround our low back, we can take a look at just the bony anatomy. In a number or cadaver studies they have found that the lumbar spine is capable of flexion and extension without damage to the bony structures in the area. However, rotation is extremely limited totaling just five degrees of rotation on average throughout the entire lumbar segment of the spine. In other studies to come up with better prediction rules in physical therapy, researchers wanted to know if movement is strict or if there is coupling that occurs. Just like everything in the human body, there is often not just one strict movement that occurs. For example, when an individual side bends their trunk in the low back area specifically there is also an associated rotation that must occur. As we just learned from the bony anatomy, that can’t happen in excess without causing bony damage or even disc damage.
The muscles in the low back really are postural in nature. Standing against gravity is pretty good strength training for these small muscles. Sometimes these small muscles will go into protective spasm which will try to limit any movement in the low back. This could be from years of faulty movement without addressing the issue, or it could be from a traumatic event like flexing or extending and twisting your low back trying to deadlift. Complete violation of the crap test (if it looks, smells, tastes, or feels like crap it is probably crap).
The other soft tissue structures in the area are things like the ligaments, disc, cartilage, and other vessels. There are a number of ligaments in the area that span either the entire spine or from one vertebra to the next. They really protect the spine from excessive flexion and extension, but just like anything else in the body they can stretch or rupture. The disc being one of the more notable ruptures (herniation) because it is filled with a material that causes local inflammation as well as the space between the vertebrae to become less. This will in turn cause nerve root irritation, protective spasm of local muscles, potential stenosis (narrowing of the canal the spinal cord is in) for us stubborn individuals, pain, walking silly, not wanting to get out of bed, etc.
A lot of times low back pain is self inflicted with terrible mechanics. Sometimes though, faulty movement patterns may be the result of poor mobility through not only the vertebrae in the low back, but also the hips or the thoracic spine (where the ribs connect to your spine). It could also be from a weak abdominal musculature that doesn’t brace or stabilize the low back well. If one has an abnormally large belly, this could cause a lot of stress through the low back as well. The list goes on and on, but the screening tools we use should show us something. Address the triplanar mobility of the hips, the rotation and extension quality of the thoracic spine, the strength and endurance of the abdominal muscles, and as a general recommendation to lose that Milwaukee tumor! These are all generalizations of course, but it is a good starting point for most individuals.